Many years ago, people lived relatively stationary lives and communicated little with others beyond their immediate circle of family, friends, and close neighbors. Today, the world is much different, and people are much more mobile and have a need for immediate communication with many others who might be far away. In order to communicate with others and cope with their mobile and complex lives, many people carry mobile electronic devices, such as laptop or notebook computers, handheld computers, cellular telephones, pagers, and PDAs (Personal Digital Assistants).
Some of these mobile devices have a rudimentary notion of user presence information. Presence information may include the reachability of a particular user through a certain system (e.g. connection to an instant messaging system) and availability of the user (e.g., the state of a reachable user, such as “available,” or “unavailable.”) Users employ presence information to gain information about others who are connected to the system and ready to receive communications. Current systems allow the users to explicitly set the state of their presence information, which persists until the user explicitly changes it. For example, users might explicitly and manually set their presence information to “available” when they turn their mobile device on and “unavailable” prior to turning their mobile device off. Users find this manual process to be cumbersome and easily forgotten, which results in inaccurate presence information, hampering its effectiveness.